Which is the lower freezing point or cold filter point of diesel

For the same oil, the general cold filter point is 1 3 higher than the condensation point. By using the method of dewaxing, the freezing point can be reduced and low-condensation diesel can be obtained.

There is no definite solidification temperature for the oil.

Freezing point refers to the maximum temperature at which all liquid fluids stop flowing under specified cooling conditions.

The solidification of an oil is inherently very different from the coagulation of a pure compound. The oil does not have a definite solidification temperature, and the so-called "solidification" only loses fluidity as a whole, and not all components become solid.

The cold filter point refers to the maximum temperature (i.e. the lowest ambient temperature used at the flow point) when the test oil passes through the filter less than 20ml per minute under specified conditions.

According to the national standard (GB252-87), the specifications of light diesel oil are divided into six grades according to the freezing point, -10, -20, -35 and -50, which indicate that the freezing point is not higher than , 35 and -50; The higher the grade, the lower the freezing point.

The cold filter point is an important indicator to measure the low-temperature performance of light diesel oil, which can reflect the actual low-temperature performance of diesel and is closest to the actual minimum operating temperature of diesel. When selecting diesel grades, users should take into account the local temperature and the cold filter point corresponding to the diesel grade. The cold filter point of No. 5 light diesel oil is 8, the cold filter point of No. 0 light diesel oil is 4, the cold filter point of No. 10 light diesel oil is 5, and the cold filter point of No. 20 light diesel oil is 14

Diesel in extremely cold areas is to be catalysted, such as -70 degrees Celsius, -50 degrees Celsius extreme cold diesel in the United States.

In general, the freezing point is 3-4 degrees higher than the cold filter point, but in special cases, the cold filter point is lower than the freezing point.

The condensation point of diesel No. 0 is 0. The brigade was defeated.

To be correct, diesel freezing is called crystallization, the grade of diesel is named after the freezing point of the oil, No. 0 diesel is to begin crystallization at 0 degrees, the reason for crystallization is that the diesel contains wax, the more wax content, the easier it is to crystallize the freezing point, the higher the freezing point, on the contrary, the wax content is low, and the freezing point is the temperature when the liquid oil loses fluidity.

No. 10 diesel freezing point is -10, -35 diesel freezing point is -35 degrees, diesel loses fluidity, the engine can not start, so diesel is to choose the grade of refueling according to the temperature.

Freezing point and cold filter point are important indicators to characterize the performance of diesel at low temperatures. The freezing point (SP) is the highest temperature at which diesel loses its fluidity in a low temperature environment; The cold filter point (CFPP) indicates the maximum temperature at which diesel can cause a filter to clog as it passes through the diesel engine's fuel supply system. For light diesel oil, the cold filter point is more important than the freezing point index in actual use.

This is because the cold filter point is directly related to the low-temperature performance of diesel, while the freezing point is mainly related to the storage and transportation of diesel. Adding a very low concentration (less than 1) of pour point depressant to diesel can greatly improve the low-temperature fluidity of diesel, and the dosing method is flexible and simple. Due to the small amount added, it will not change other performance indicators of diesel, and at the same time, the unit production cost of diesel is much lower than the cost of other condensation and filtration reduction methods or ways.

Diesel solidifies at lower temperatures because it contains a certain amount of wax (i.e., n-alkanes) in it, which gradually precipitates and forms wax crystals when the temperature is lowered. Finally, the oil is encapsulated in it, causing the oil to lose its fluidity and appear to solidify.

After adding the de-elevating and de-escalating agent to the diesel fuel, when the temperature is reduced, the wax crystal will be adsorbed on the surface of the wax crystal as soon as it is formed, which prevents the mutual adhesion between the wax crystals and prevents the formation of a continuous crystal network, so that the wax crystal particles are more fine and can pass through the filter screen well. The function of the pour point depressant to destroy or change the wax crystallization can reduce the cold filter point and freezing point of diesel fuel.

Light diesel oil is divided into different grades according to the freezing point, and each grade has a corresponding freezing point and cold filter point index. No. 0 light diesel oil means that the condensation point of this grade of diesel fuel is not higher than 0, and its corresponding cold filter point index is not higher than +4. No. 0 diesel with a condensation point of 0 can only be used normally at temperatures higher than its cold filter point +4, and the diesel fuel can no longer pass through the filter screen (or filter) at temperatures below the cold filter point; When the temperature drops to 0, the oil loses its fluidity and appears to solidify.

The effect of the pour point depressant depends not only on the performance of the pour point depressant itself, but also on the composition of the oil added. A pour point depressant is added to the diesel fuel with different compositions, and the amplitude (i.e., susceptibility) of the cold filter point is quite different, so the quarrel should first select the best pour point depressant according to the susceptibility of various pour point depressants to the oil. Secondly, according to the composition and properties of the added oil, it is necessary to determine the optimal amount of addition through a small test in the laboratory.

Low condensation point diesel is a special type of diesel, his petroleum ether particles are smaller, the melting point is low, it has good fluidity, and it is not easy to solidify and crystallize in a low temperature environment. Paraffin wax is a wax-like substance with strong coagulation and crystallization ability. Diesel containing more paraffin will lead to an increase in the freezing point of diesel, which is easy to solidify in a low temperature environment, resulting in insufficient fuel supply and even fuel system blockage.

Therefore, the paraffin content in low-condensing point diesel needs to be less than that of conventional diesel. In the low temperature environment, the auto-ignition temperature of diesel fuel will increase, and the combustion capacity will decrease, which will cause the engine to fail to start and work normally. Low condensation point diesel fuel inhibits the precipitation and crystallization of diesel fuel in a low temperature environment by controlling the molecular weight and molecular weight distribution of the fuel, ensuring the normal operation of the fuel**.

Low condensation point diesel has a wide range of applications, not only for vehicles, boats, generator sets and other mechanical equipment, but also for urban heating, industrial heat and other fields of fuel.

The freezing point of diesel depends on the label, and the freezing point of different labels is also different. The freezing point of No. 0 diesel is 0 degrees, -20 is minus 20 degrees, and so on.

A layer of wax is formed on the surface of the oil, and the lower the temperature, the more wax is formed, and the No. 0 diesel will only form a thin layer of wax in the static state of about -10 degrees, but it remains liquid under the wax layer and can be pumped.

The most important use of diesel is in diesel engines for vehicles and ships. Compared to gasoline, diesel has a high energy density and a low fuel consumption rate. Diesel has low energy consumption, so some small cars and even high-performance car wheels also switch to diesel.

Take vehicle diesel (China VI) as an example:

The condensation point of diesel fuel is also different for different license plates.

1. No. 5 diesel: the condensation point next to the balance is not higher than 5 2. No. 0 diesel: the condensation point is not high and the oak is 0

3. -10 diesel: the freezing point is not higher than -10 4. -20 diesel: the freezing point is not higher than -20

5. -35 diesel: the freezing point is not higher than -35 6. -50 diesel: the freezing point is not higher than -50

National VI bending diesel testing indicators.

Cold filter point of diesel: the maximum temperature when the diesel fuel is cooled under the specified conditions, when the diesel cannot flow through the filter or the 20ml diesel oil flows through the filter for more than 60 seconds, or the diesel fuel cannot completely flow back to the test cup, which is expressed by .

The freezing point of diesel fuel refers to the maximum temperature of diesel fuel under the specified test conditions, when the oil surface of the cooled sample no longer moves, all of which are expressed in . The cold filter point refers to the maximum temperature (i.e. the lowest ambient temperature used at the flow point) when the test oil passes through the filter less than 20ml per minute under specified conditions.

The diesel cold filter point refers to the diesel sample cooled under the specified conditions, and is sucked under the pressure of 1961pa (200mm water column), so that the cooled diesel sample passes through a 363 mesh filter, and the minimum temperature when the filter is blocked to the point where it cannot pass or the flow rate is less than 20ml min. The lower this temperature, the better the fluidity of the diesel at low temperatures and the less likely it is to clog the filter.

The freezing point of diesel fuel is the maximum temperature at which the oil is cooled to the point where it loses its fluidity under specified conditions. When the content of n-alkanes in diesel fuel is high and the boiling point is high, the freezing point is also high. Generally, the condensation point of diesel is lower than the ambient temperature of 3 -5, therefore, with the change of seasons and regions, it is necessary to use different grades of commercial diesel, that is, different condensation points.

Test factors for the cold filter point of diesel fuel.

The experimental conditions affecting the determination of the cold filter point of diesel fuel were experimented and discussed, using the No. 0 vehicle diesel with a cold filter point higher than -20 as a sample. The results show that the lower the temperature of the cold bath, the faster the cooling rate, and the measured cold filter point result is low, and vice versa, it needs to be controlled at 34 0 5The lower the initial temperature of the sample, the higher the cold filter point measurement result, and vice versa, the lower it needs to be controlled at 30 5.

When the number of suctions is high to a certain extent, the cold filter point measurement result will be low. The closer the thermometer is to the bottom of the test cup, the lower the cold filter point measurement result, and vice versa, the higher it needs to be controlled. Therefore, the strict control of various conditions in the experimental process is the key to accurately determine the results of cold filtration point.

The authoritative answer from the experts of HAUTE diesel anticoagulant is:

Cold filter point of diesel: It is the maximum temperature that will cause the filter screen to clog when the diesel fuel passes through the diesel engine fuel supply system (when the temperature is lower than the cold filter point, the diesel car filter will be blocked). When the temperature of a grade of diesel oil is lower than a certain value, the phenomenon of poor oil supply will occur, because when the diesel engine is working, the diesel is injected into the cylinder through the coarse and fine filters, and then through the high-pressure pump and fuel injector.

When the diesel temperature drops to the cold filter point temperature, the wax crystals formed will block the filter and affect the normal oil supply of the oil circuit, which in turn will affect the normal operation of the engine.

Freezing point of diesel: It is the highest temperature that indicates that diesel loses fluidity in a low temperature environment (when the temperature is lower than the freezing point, diesel will solidify and wax, affecting the storage, transportation or use of diesel). A grade of diesel fuel solidifies and no longer flows when the temperature falls below a certain value, because diesel contains a certain amount of wax (i.e., n-alkanes), which gradually precipitate out and form wax crystals when the temperature decreases.

As the temperature decreases further, the wax crystals grow rapidly, first forming planar crystals, which are interconnected to form a three-dimensional network structure, in which the oil is encapsulated, causing it to lose its fluidity and appear solidified.